Myopia Flashcards
Definition
Parallel rays come to focus in front of retina when the eye at rest
Etiology or causes of myopia
axial mypia : longer axial length
Refractive myopia
Anterior dislocation of lens
DM (hyperglycemia)
Causes of refractive myopia:
Dt increase of curvature of the cornea or the lens (keratoconus, lenticonus, subluxation)
Or increase refractive index of the lens nucleus in ** senile nuclear cataract.**
Symptoms
Defective far vision
late presbyopia
In pathological myopia:
Floater, phostopsia, defective night vision and field defect
What are signs that you can see in general in patient with myopia
Lage globe
Large pupil
Large cornea
Deep A/C
(All above are opposite in hypermetropia)
Pseudoproptosis
What can you find with fundoscopy (retina) in patients with myopia
Tigroid (tessellated fundus)
Myopic crescent
Choroido-retinal degeneration
Posterior staphyloma (temporal to O.D)
Lattic degeneration
Lacquer cracks
What is myopic crescent
Reaction of the retina and choroid from optic disc with exposure of sclera (give white color) may be:
Temporal crescent( temporal to OD)
Annular crescent (surrounding O.D)
White atrophic area surrounded by pigmentation
It is due to atrophy of retina and choroid showing sclera
Choroio-retinal degeneration
Lattice degeneration most often located in
Temporal and superior
Lattice degeneration related to:
Retinal detachment
Because transform to retinal tear and hole
What are lacquer cracks:
They are ruptures in the RPE-Bruch membrane complex characterized clinically by fine, irregular, yellow lines, may lead to Subretinal ‘coin’ hemorrhage
Signs that you find it in the vitreous
Liquefaction and vitreous floaters
What is fuch’s spot
Black area at macula, it is due to subretinal hge, which lead to loss of central vision
Investigations that you will request to confirmation of myopia
Autorefractometry
Retinoscopy
Complications of myopia
Squint( divergent)
